Portion of a shoe bottom



FIG. 1 is a perspective view of the portion of a shoe bottom showing my new design;

FIG. 2 is a bottom plan view thereof; and,

FIG. 3 is a front elevational view thereof.

The broken line showing the sole in the figures is for illustrative puposes only and forms no part of the claimed design. 

The ornamental design for a portion of a shoe bottom, as shown and described. 